Photocatalytic Glucose Reforming for Formic Acid on 2D Amorphous MoO_3-x/TNTs Heterojunction in Pure Water

Formic acid is a promising hydrogen-storage material and biohydrogen production intermediate, offering sustainable biomass-derived alternative processes. Herein, a 2D amorphous molybdenum oxide/titanium oxide nanotubes (MoO_3-x/TNTs) heterojunction with amorphous/crystalline interfaces is designed and fabricated by supercritical CO₂, with which the photocatalytic reforming of glucose for formic acid is realized in pure water. The HCOOH yields 14.8% for glucose and 22% for glycerol, are achieved in pure water at room temperature with 2 bars O₂ atmosphere within 6 h under 365 nm light with 5 mW cm^-2. The photoinduced Mo⁶⁺-catalyzed ligand-to-metal charge transfer and the enhanced adsorption energy of glucose molecules on the MoO_3-x surface in the MoO_3-x/TNTs heterojunction facilitate the cleavage of CC bonds in polyhydric alcohol skeletons, leading to the formation of HCOOH. Under light excitation, MoO_3-x transfers electrons to TNTs due to the defect state, synergizing with the generated •OH radicals in the system. This results in reversible cycling between Mo⁶⁺ and Mo⁵⁺, thereby ensuring catalytic persistence. Therefore, this study demonstrates a photocatalytic strategy for the sustainable production of value-added chemicals from biomass under eco-friendly conditions, using easily recyclable heterogeneous catalysts in pure water.